Underground mine ventilation curtain or barrier

ABSTRACT

A mine ventilation curtain ( 1, 20 ) is provided comprising, in the operative condition, a generally upright curtain or barrier extending from a foot wall ( 4 ) in an underground mine to an overhanging hanging wall ( 5, 25 ). The curtain has a foot wall compartment ( 3, 22 ) of a flexible sheet material with the footwall compartment being operatively filled with a suitable optionally settable fluent material ( 13, 27 ) such that the lower edge of the curtain or barrier substantially adopts an undulating shape of the adjacent foot wall. The fluent material is selected from a suitably heavy liquid and an optionally settable slurry of grout or backfill material. The mine ventilation curtain may be a flexible ventilation curtain ( 2 ) extending upwards from the foot wall compartment ( 3 ) and having its uppermost edge held in close association with the hanging wall. Alternatively, the mine ventilation curtain may be a generally rigid ventilation barrier ( 20 ) in the form of longitudinal segments each of which comprises a series of optionally interconnected superjacent compartments ( 22, 23, 24 ) extending from the footwall to the hanging wall with the uppermost compartment ( 24 ) adopting an undulating shape of the adjacent hanging wall.

FIELD OF THE INVENTION

This invention relates to underground mine ventilation curtains orbarriers and, in particular, but not exclusively, to in-stopeventilation control curtains or barriers used for creating ventilationpassages between the hanging wall and foot wall in a mine stope.

In this specification is to be understood that the term the ventilationcurtain is intended to include flexible ventilation curtains andgenerally rigid ventilation barriers.

BACKGROUND TO THE INVENTION

In the operation of a typical large tabular ore body in an undergroundmine, ventilation in the form of the provision of fresh, cool air to theentire extent of the mine workings is essential. The nature of thetabular ore deposits results in wide narrow mining stopes with vastworked-out back areas, which, if left open, waste large amounts of aircooling them unnecessarily.

The flow of fresh air through a mine is required for two principalreasons, firstly, to provide an acceptable climatic working environmentfor all underground personnel, and, secondly, to flush toxic fumesresulting from explosive blasts and any airborne combustion products inthe event of underground fires out of the mine.

The necessary ventilation is typically generated by extractor- and/orcompressor fans by way of a carefully designed network of shafts andtunnels and thence through the working areas. Ventilation of dead-ends,such as development ends, is generally provided by means of blower fansthrough dedicated ducting.

The ventilation of a mine is reported to account for one the largestproportions of a mine's energy consumption. In order to preventexpensive waste, stope back areas are closed off to air flow by means ofventilation curtains or barriers.

Ventilation curtains have been used for a very long time. Generally,modern flexible ventilation curtains consist of a geotextile that issuspended from mine support units that are spaced apart in the normalcourse of events. One of the main problems with conventional flexibleventilation curtains is air leakage above and below the curtain wheregaps are left between the upper and lower edges of the curtain and tothe irregular hanging wall and footwall.

OBJECT OF THE INVENTION

It is an object of this invention to provide a mine ventilation curtainthat overcomes, at least to some extent, leakage problems of the generaltype indicated above.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a mine ventilationcurtain comprising, in the operative condition, a generally uprightcurtain extending from a foot wall in an underground mine to anoverhanging hanging wall, the curtain being characterised in that thelower region thereof in contact with the foot wall is defined by a footwall compartment of a flexible sheet material with the footwallcompartment being operatively filled with a suitably heavy optionallysettable fluent material such that the lower edge of the curtain orbarrier substantially adopts an undulating shape of the adjacent footwall.

Further features of the invention provide for the fluent material to beeither a liquid or a slurry of grout or backfill material and; for theflexible sheet material to be permeable material for allowing water of aslurry introduced into the foot wall compartment to escape whilstretaining solid particulate material therein, the flexible sheetmaterial typically being a geotextile material or a suitable membrane;and for the particulate material optionally to be a settable material,typically a cementitious grout.

In a first variation of the invention a generally flexible ventilationcurtain extends upwards from the foot wall compartment and has itsuppermost edge held in close association with the hanging wall by anysuitable means according to circumstances. In a preferred arrangement, atension member extends along the uppermost edge of the flexibleventilation curtain, typically within a seam formed along such edge andthe upper edge of the flexible curtain may be held against the hangingwall in at least some recessed areas thereof by means of spring loadedor other lightweight telescopic props. The uppermost edge of theflexible ventilation curtain may also be provided with eyelets suitablefor receiving anchor bolts passing therethrough for attachment to thehanging wall. Of course, combinations of props and anchor bolts may beused as well as any other suitable support means.

In a second variation of the invention a generally rigid ventilationbarrier is in the form of longitudinal segments each of which comprisesa series of optionally interconnected superjacent compartments extendingfrom the footwall to the hanging wall with the uppermost compartmentadopting an undulating shape of the adjacent hanging wall. The footwallcompartment is preferably the widest with superjacent compartmentsdecreasing in width so that, in cross-section, the generally rigidventilation barrier has a wide base and appreciably narrower upper edgeso as to render it free standing on an inclined foot wall. Preferablyall of the compartments are interconnected and a filler inlet,preferably a nonreturn filler valve, is provided preferably in an upperregion thereof, typically the uppermost compartment.

The invention also provides, in the uninstalled condition and as anarticle of commerce, a flexible ventilation curtain having a footwallcompartment formed along one edge thereof and means along the oppositeedge for in enabling it to be held against a hanging wall, in use, theventilation curtain being adapted to form, in the operative condition, aventilation curtain as defined above.

The invention still further provides, in the uninstalled condition andas an article of commerce, a barrier member comprising a series ofinterconnected flexible compartments and at least one filler inlet, thebarrier member being adapted to be inflated by filler material to form,in the operative condition, a generally rigid ventilation barrier asdefined above.

In order that the invention may be more fully understood one embodimentof each of the two variations thereof will now be described withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:—

FIG. 1 is a schematic section taken through a flexible ventilationcurtain according to the first variation of the invention;

FIG. 2 is a schematic front elevation of a length of such ventilationcurtain;

FIG. 3 is a schematic plan view showing one possible arrangement of aflexible ventilation curtain relative to a series of support packs in amine stope;

FIG. 4 is a schematic section taken through a generally rigidventilation barrier according to the second variation of the invention;

FIG. 5 is a schematic front elevation of a length of the ventilationbarrier illustrated in FIG. 4; and,

FIG. 6 is a schematic plan view showing one possible arrangement of aseries of ventilation barriers relative to a series of support packs ina mine stope.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the first variation of the invention illustrated inFIGS. 1 to 3 a flexible mine ventilation curtain, generally indicated bynumeral (1), comprises, in the operative condition, a generally uprightcurtain (2) extending from a foot wall compartment (3) that engages thefootwall (4) in an underground mine to an overhanging hanging wall (5).

Both the curtain and footwall compartment are made of a water permeableflexible sheet material, typically a geotextile material or a suitablemembrane, and the footwall compartment could be made by stitching thesheet material back upon itself to provide a suitable cross-sectionalsize of footwall compartment. The flexible sheet material is selected sothat it allows water to pass through it whilst retaining solids such asa cementitious grout or backfill material within the footwallcompartment. The footwall compartment has a nonreturn inlet valve (6)for the introduction of slurry into the compartment.

The ventilation curtain extends upwards from the foot wall compartmentand has its uppermost edge (7) held in close association with thehanging wall. In this embodiment of the invention a tension member (8)extends along the uppermost edge of the ventilation curtain in a largeseam (9) formed along such edge. The seam is large enough to enable theupper edge of the curtain to be held against the hanging wall in atleast some recessed areas thereof by means of spring loaded or otherlightweight telescopic props (10). The uppermost edge of the ventilationcurtain may, in addition, or in the alternative, be provided witheyelets (11) suitable for receiving anchor bolts passing therethroughfor attachment to the hanging wall or to stope support units. Of coursecombinations of props and anchor bolts may be used as well as any othersuitable support means.

As indicated above, the invention extends to the uninstalled ventilationcurtain and, such a curtain is installed by suspending its upper edgefrom the tension member that itself can be attached to the upper ends ofsupport packs (12), as shown in FIG. 3. Slurry of a suitable grout orbackfill material (13) is then introduced into the footwall compartmentso that the lower edge of the curtain substantially adopts theundulating shape of the adjacent foot wall thereby forming an effectiveclosure therewith. The upper edge of the flexible ventilation curtaincan then be attached to the recessed areas of the hanging wall by meansof lightweight props and/or anchor bolts to form an effective closuretherewith. As shown in FIG. 3, the ventilation curtain can be of azigzag shape between adjacent support packs. However, it could alsoextend on one side of the support packs.

Turning now to the second variation of the invention that is illustratedin FIGS. 4 to 6, a generally rigid ventilation barrier, generallyindicated by (20) is formed in longitudinal segments each of whichextends between two adjacent support packs (21), as shown in FIG. 6.Each segment comprises a series of, in this instance four,interconnected superjacent compartments starting at the footwallcompartment (22) with two intermediate compartments (23) and anuppermost compartment (24) adopting the undulating shape of the adjacenthanging wall (25).

The footwall compartment is the widest with superjacent compartmentsdecreasing in width so that, in cross-section, the barrier has a widebase and an appreciably narrower upper edge. This construction lowersthe centre of gravity and renders the barrier free standing on aninclined footwall whilst also saving on materials and erection time. Theuppermost compartment (24) is provided with a nonreturn filler valve(26).

As will be clear from the aforegoing the barrier segments are erected byintroducing a slurry of grout or backfill material (27) into thenonreturn filler valve. The slurry flows downwards to firstly fill thefootwall compartment with the lower wall deforming to adopt theundulating shape of the footwall and thereafter inflates the superjacentcompartments and finally the uppermost compartment the uppermost wall ofwhich also deforms to adopt the undulating shape of the hanging wall.

It will be understood that numerous variations may be made to theembodiments of the invention described above without departing from thescope hereof. In particular, the footwall compartment, and indeed thesuperjacent compartments in the instance of the ventilation barrier,need not be made of a permeable material but could be, for example,waterproof in which instance water may be used as a fluent heavymaterial.

It is also within the scope of the invention that compressed air couldbe used to inflate a barrier segment of the type described above. Ofcourse, the advantage of using a non-setting fluent material is that thebarrier segments can be deflated and reused should this be practicable.

1. A mine ventilation curtain (1, 20) comprising, in the operativecondition, a generally upright curtain or barrier extending from a footwall (4) in an underground mine to an overhanging hanging wall (5, 25),the curtain being characterised in that the lower region thereof incontact with the foot wall is defined by a foot wall compartment (3, 22)of a flexible sheet material with the footwall compartment beingoperatively filled with a suitable optionally settable fluent material(13, 27) such that the lower edge of the curtain or barriersubstantially adopts an undulating shape of the adjacent foot wall.
 2. Amine ventilation curtain as claimed in claim 1 in which the fluentmaterial is selected from a suitably heavy liquid and a slurry of groutor backfill material.
 3. A mine ventilation curtain as claimed in claim2 in which the flexible sheet material is a permeable material forallowing water of a slurry introduced into the foot wall compartment toescape whilst retaining solid particulate material therein.
 4. A mineventilation curtain as claimed in any one of the preceding claims inwhich the particulate material is a settable material.
 5. A mineventilation curtain as claimed in any one of the preceding claims inwhich the ventilation curtain is a flexible ventilation curtain (2)extending upwards from the foot wall compartment (3) and having itsuppermost edge held in close association with the hanging wall.
 6. Amine ventilation curtain as claimed in claim 5 in which the uppermostedge (7) of the flexible ventilation curtain is held in closeassociation with the hanging wall (5) by a tension member (8) extendingalong the uppermost edge of the ventilation curtain.
 7. A mineventilation curtain as claimed in either one of claim 5 or 6 in whichthe uppermost edge of the ventilation curtain has a seam (9) formedtherealong and the upper edge of the curtain is held against the hangingwall in at least some recessed areas thereof by means selected fromspring loaded or other lightweight telescopic props (10) and eyelets(11) suitable for receiving anchor bolts passing therethrough.
 8. A mineventilation curtain as claimed in any one of claims 1 to 4 in which theventilation curtain is a generally rigid ventilation barrier (20) in theform of longitudinal segments each of which comprises a series ofoptionally interconnected superjacent compartments (22, 23, 24)extending from the footwall to the hanging wall with the uppermostcompartment (24) adopting an undulating shape of the adjacent hangingwall.
 9. A mine ventilation curtain as claimed in claim 8 in which thefootwall compartment (22) is the widest with superjacent compartments(23, 24) decreasing in width so that, in cross-section, the barrier hasa wider base and an appreciably narrower upper edge thereby rendering itfree standing on an inclined foot wall.
 10. A mine ventilation curtainas claimed in either one of claim 8 or 9 in which all of thecompartments are interconnected and a filler inlet valve (26) isprovided.
 11. A flexible mine ventilation curtain in the uninstalledcondition and having a footwall compartment formed along one edgethereof and means along the opposite edge for enabling it to be heldagainst a hanging wall, in use, the ventilation curtain being adapted toform, in the operative condition, a ventilation curtain as claimed inany one of claims 5 to
 7. 12. A mine ventilation barrier segment in theuninstalled condition comprising a series of interconnected compartmentsand at least one filler inlet, the barrier member being adapted to beinflated by filler material to form, in the operative condition, aventilation barrier as claimed in any one of claims 8 to 10.